Ultrahigh-Throughput Screening of High-β-Xylosidase-Producing Penicillium piceum and Investigation of the Novel β-Xylosidase Characteristics

A droplet-based microfluidic ultrahigh-throughput screening technology has been developed for the selection of high-beta-xylosidase-producing Penicillium piceum W6 from the atmospheric and room-temperature plasma-mutated library of P. piceum. beta-xylosidase hyperproducers filamentous fungi, P. piceum W6, exhibited an increase in beta-xylosidase activity by 7.1-fold. A novel beta-D-xylosidase was purified from the extracellular proteins of P. piceum W6 and designated as PpBXL. The optimal pH and temperature of PpBXL were 4.0 and 70 degrees C, respectively. PpBXL had high stability an acidic pH range of 3.0-5.0 and exhibited good thermostability with a thermal denaturation half-life of 10 days at 70 degrees C. Moreover, PpBXL showed the bifunctional activities of alpha-L-arabinofuranosidase and beta-xylosidase. Supplementation with low-dose PpBXL (100 mu g/g substrate) improved the yields of glucose and xylose generated from delignified biomass by 36-45%. The synergism between PpBXL and lignocellulolytic enzymes enhanced delignified biomass saccharification, increased the Xyl/Ara ratio, and decreased the strength of hydrogen bonds.

Automated summary

A droplet-based microfluidic ultrahigh-throughput screening technology was developed to select high-beta-xylosidase-producing Penicillium piceum W6 from a mutated library. A novel beta-D-xylosidase with bifunctional activities was purified and identified from this strain. The addition of this enzyme significantly enhanced the yields of glucose and xylose from delignified biomass.